/*
 * Copyright (C) 2009 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

package com.googlecode.sl4a.jsonrpc;

import com.duy.pascal.ui.utils.DLog;
import com.googlecode.sl4a.SimpleServer;
import com.googlecode.sl4a.event.Event;
import com.googlecode.sl4a.rpc.MethodDescriptor;
import com.googlecode.sl4a.rpc.RpcError;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;

/**
 * A JSON RPC server that forwards RPC calls to a specified receiver object.
 *
 * @author Damon Kohler (damonkohler@gmail.com)
 */
public class JsonRpcServer extends SimpleServer {

    private final RpcReceiverManagerFactory mRpcReceiverManagerFactory;
    private final String mHandshake;

    /**
     * Construct a {@link JsonRpcServer} connected to the provided {@link RpcReceiverManager}.
     *
     * @param managerFactory the {@link RpcReceiverManager} to register with the server
     * @param handshake      the secret handshake required for authorization to use this server
     */
    public JsonRpcServer(RpcReceiverManagerFactory managerFactory, String handshake) {
        mHandshake = handshake;
        mRpcReceiverManagerFactory = managerFactory;
    }

    @Override
    public void shutdown() {
        super.shutdown();
        // Notify all RPC receiving objects. They may have to clean up some of their state.
        for (RpcReceiverManager manager : mRpcReceiverManagerFactory.getRpcReceiverManagers()) {
            manager.shutdown();
        }
    }

    @Override
    protected void handleConnection(Socket socket) throws Exception {
        RpcReceiverManager receiverManager = mRpcReceiverManagerFactory.create();
        BufferedReader reader =
                new BufferedReader(new InputStreamReader(socket.getInputStream()), 8192);
        PrintWriter writer = new PrintWriter(socket.getOutputStream(), true);
        boolean passedAuthentication = false;
        String data;
        while ((data = reader.readLine()) != null) {
            DLog.v("Received: " + data);
            JSONObject request = new JSONObject(data);
            int id = request.getInt("id");
            String method = request.getString("method");
            JSONArray params = request.getJSONArray("params");

            // First RPC must be _authenticate if a handshake was specified.
            if (!passedAuthentication && mHandshake != null) {
                if (!checkHandshake(method, params)) {
                    SecurityException exception = new SecurityException("Authentication failed!");
                    send(writer, JsonRpcResult.error(id, exception));
                    shutdown();
                    throw exception;
                }
                passedAuthentication = true;
                send(writer, JsonRpcResult.result(id, true));
                continue;
            }

            MethodDescriptor rpc = receiverManager.getMethodDescriptor(method);
            if (rpc == null) {
                send(writer, JsonRpcResult.error(id, new RpcError("Unknown RPC.")));
                continue;
            }
            try {
                send(writer, JsonRpcResult.result(id, rpc.invoke(receiverManager, params)));
            } catch (Throwable t) {
                DLog.e("Invocation error.", t);
                send(writer, JsonRpcResult.error(id, t));
            }
        }
    }

    private boolean checkHandshake(String method, JSONArray params) throws JSONException {
        return !(!method.equals("_authenticate") || !mHandshake.equals(params.getString(0)));
    }

    private void send(PrintWriter writer, JSONObject result) {
        writer.write(result + "\n");
        writer.flush();
        DLog.v("Sent: " + result);
    }

    @Override
    public void onEventReceived(Event event) {

    }
}
